Efforts to reduce and control the quantity of air pollutants in the atmosphere have resulted in the development of instrumentation for measuring air pollutants such as the oxides of nitrogen by measuring the light resulting from their chemiluminescent reaction with ozone. United States patents which are typical of such instruments include Nos. 3,528,779 to A. Fontijn; 3,692,485 to R. M. Neti et al; 3,700,896 to H. H. Anderson; 3,746,513 to A. Warnick et al; 3,746,514 to A. D. Colvin et al; 3,749,929 to G. W. Wooten; and 3,849,653 to R. R. Sakaide.
In these prior art devices it has been necessary either to use a large, fragile, and costly photomultiplier tube in combination with the chemiluminescent detection devices in order to measure the small amount of light from the reaction, or to abandon the chemiluminescent technique in order that the greater light output available from bioluminescent reactions may be used to permit the use of a low impedance solid state cadmium sulfide detector as, for example, in Sakaide. Neither of these alternatives is entirely satisfactory.
It is an object of the present invention to provide a device for the continuous detection of light emitted by the chemiluminescent reaction of ozone and nitric oxide which utilizes a high impedance solid state detector and associated electronics including a high gain current amplifier for greater overall detector sensitivity, in combination with a specifically designed reaction chamber to increase reaction light output sufficiently to permit the use of the more sensitive high impedance detector.